Can't run models

Hi,

I'm a newbie that tried to run models from the RapidminerGo and got this error:
Generalized Linear Model, Deep Learning, Decision Tree, Random Forest, Gradient Boosted Trees, Support Vector Machine com.rapidminer.operator.UserError: The attribute <em>google)</em> was already present in the example set. at com.rapidminer.example.SimpleAttributes.rename(SimpleAttributes.java:183) at com.rapidmin...

Do you know what I should change in my data in order to make it work?

Thanks,
Erez